The present invention relates to a cylinder head gasket for an internal combustion engine. More particularly, the invention relates to a multi-layer metal cylinder head gasket having a sealing member that floats in a cylinder opening, corresponding to a combustion chamber, of a spacer layer of the multi-layer gasket.
Gaskets are often used as a seal between mating mechanical components. One common application involves gasket placement between the engine block and cylinder head of an internal combustion engine. Cylinder head gaskets typically extend around cylinder bores to provide a combustion seal, maintaining the high temperature gases of combustion within the cylinder bores. Simultaneously, the gaskets also seal fluid flow openings such as coolant and oil openings to prevent undesirable mixing. A cylinder head gasket bears the load from a bolted connection of the mechanical components and relies upon that load to provide both the combustion and fluid flow seals.
In a metal laminate gasket for an internal combustion engine, the gasket is formed from a plurality of metal plates laminated together. The metal plates provide structural support within the joint between the cylinder head and engine block, and provide radial strength to resist gasket blow-out due to pressure from the combustion chamber.
Known gaskets use any of several types of combustion seals. One type, known as a flanged combustion seal ring, is essentially comprised of a wire, having a generally circular cross-sectional area. The wire may be inserted within an open end of a U-shaped flange with opposing legs of the flange engaging opposite faces of a main gasket body about the combustion opening. A clamping load is applied to the flanged portion of the gasket at the point of contact, deforming the ring""s circumference to seal out combustion gases. Using such a configuration, the clamping load required to seal against combustion gases is typically higher because the force is distributed between two rings and may tend to promote undesirable gasket and engine-block distortion.
Another type of combustion seal relies on a floating yieldable ring installed separately from the gasket. The floating ring is installed within a channel formed about the combustion chamber hole. A force applied to such a ring is concentrated at the point of contact, deforming the ring""s circumference to effectively seal out combustion gases. However, such a seal ring must be separately installed, and may migrate prior to being subject to a clamping load, resulting in an imperfect seal. Further, the channel receiving the ring must be separately machined in the engine block to accommodate the ring, complicating gasket manufacture.
The present invention is directed to a cylinder head gasket of an internal combustion engine having at least one cylinder bore opening. The gasket is clamped between a cylinder head and an engine block to sealingly engage a mating surface on the cylinder head and engine block.
The gasket is a multi-layer metal gasket adapted to cooperate between an engine block and an engine head comprising an inner spacer layer sandwiched between top and bottom surface layers. The inner spacer layer provides cylinder openings designed to correspond and sealingly engage with each cylinder bore in the engine block. At least one channel, cut in the spacer layer, extend outwardly from a periphery defined by the circumference of each cylinder opening.
A combustion sealing member formed with at least one tab extending outwardly from a periphery defined by the circumference of the sealing member is received into each cylinder opening. The sealing members orient in the cylinder opening with the tab residing in a channel. The tab is embossed at its distal end. Upon positioning in the cylinder opening, the tab is eyeletted with an eyelet to the top and bottom layers. The tabs retain the sealing member in the cylinder opening, positively locating the sealing member over the cylinder bores on the engine block during installation and permitting the sealing member to float in the cylinder opening during operation of the engine independently of the spacer layer.
The tabs projecting outwards from the sealing members and the channels cut outwards from the periphery of the cylinder openings of the inner spacer layer that receive the tabs over come known problems in gasket design. First, the channels by receiving the tabs connected to the upper and lower surface layers insure proper alignment of the sealing member over the cylinder bore during installation of the gasket. Additionally, once installed, the tabs permit the sealing member to float in the cylinder opening independent of the inner spacer layer to flexibly adapt to engine movements during operations. This flexibility of the floating sealing member increases the effectiveness of the seal of the gasket about the cylinder bores.